I am working on a 56 Mercury with the factory 312 and automatic trans. I knew it was low on AT fluid so bought some type F when I was in town getting oil for it. I started it up quick today (first time in many years). I only let it run for a few seconds. I checked the service manual and the car calls for type A. I did a google search and came up with plenty of answers. Some say A and F are compatible, some say Dexron III is the replacement. I already have the F here but can make another trip to town if that will not work. I don't want to cause any harm. I know I can always get good advice here, so thanks in advance.
You won't hurt it using F, A, or III. Used to be the trick to getting slightly firmer shifts in transmissions that called for A or Dexron, was to use type F in them. I never really noticed a difference.
I read that the old B&M Trickshift fluid was really Type F. It was used by a lot of guys in a lot of different transmissions with no problems. I used type F in my 85 E350 motor home with C6 transmission. Didn't feel any difference. I didn't realize it was supposed to have Dex 3 in it.
I used to teach automatic transmission rebuilding and had a Storm/Vulcan transmission dynamometer. It held 55 gallons of ATF and the only transmissions I had that required a different fluid were the C4, C6 and FMX Ford transmissions. We always kept type F in the dyno. It worked fine in Torqueflites and GM transmissions of the day. As others have said using type F was almost the same as the B&M fluid and cheaper.
In my 51 Merc-O- Matic, I drained and filled with type F and it it shifted good. It was in fact a firmer shift. A couple months later I drained it and put in Dex/Merc III. It also shifted good. But a little "friendlier" of a shift. I liked it better. I've seen Borg Warner literature that specifically states Dexron was designed to be backwards compatible with type A. I don't think it matters much. I've even heard personal accounts of Ford-O guys mixing the 2 types just to say they did. Also, all the Studebaker guys say to use DexMerc in place of A in their Flightomatic and Borg 3 band DG transmissions.
I always heard type F wasn’t as slick as mercon or dextron. I’ve used straight hydraulic fluid in race transmissions. Works good too just doesn’t have the additives for the various clutch materials.
What you say right here is what I heard Ford did when rebuilding a customers transmission that shifted to hard for their liking.
I do not like to mix fluids. It is a personal thing and I am sure that i have mixed fluids in the past. I was reading one time that the F stands for Friction and not Ford as I had always believed. Sometimes the things you learn will surprise you. LOL When I was building a Turbo 350 once in then '90s I was using a lot of TCI pieces and while talking with a TCI tech guy (on the phone, you ought to try that some time ) he suggested that I use Type F in the tranny. So against all my backward beliefs I did it. I don't know if it worked any better because I did not try the transmission with Dextron first. Buit it didn't seem to hurt anything.
Another fine version of ATF fluid is type FA. I guess this meant something between F and A types. All I know is the guy I bought my 58 Buick from said to use FA. It is getting harder to find, so I might try blending the two types. My car has the infamous FLITE PITCH DYNAFLOW.
Mercon/Dexron III is the closest equivalent to Type A that I'm aware of. The Jetaway Hydramatic I run in my 56 Olds calls for Type A, and in the interest of keeping it as happy as can be, I have tried to keep it full of the closest equivalent. That being said, my trans leaks like a bastard and I put in pretty much whatever there is laying around in the premise that the wrong fluid is better than no fluid. I've put regular old Type F in there, ATF+4, Mercon/Dexron.... in basically any combination, and it doesn't seem to make a difference. The trans shifts fine and I keep driving. I've always run ATF in my 727, so I can't really speak to how it shifts versus anything else. But it shifts very hard, which I attribute more to the TCI shift kit and valve body than the fluid. I personally like that very hard, pronounced, and strong shift.
Leaks are a pain in the butt. Just a thought. I worked on a 56 Buick years ago, might have been a similar trans to your Olds. It leaked bad out the front and we assumed it was the front seal. Pulled that front inspection cover and IIRC, there were a bunch of small bolts around the outside of the flex plate/converter, probably a 2 piece. Anyway, those bolts weren't very tight and I'm guessing there is an o ring there. I retightened those and the leak stopped. That was a great relief. You may have checked that already, but thought I would mention it.
Not to high-jack this thread, but I think my biggest issue in terms of the leak is a likely a failed o-ring where the dipstick tube enters the trans case. The Jetaway has an internal groove cut in the trans case where the smooth dipstick tube slides in. This seals the tube, but it often fails over time. It looks like a previous owner tried to smear silicone on it to stop the leak, to no avail. The biggest leak I get is after the trans is full, I take a drive, then shut the car off. My theory is that the fluid level, which is checked with the engine running and trans in neutral, is set then, but then when the engine is shut off, the fluid in the torus drains back to the case, fills the pan over the height of the dipstick tube, and pours out all over the ground. I need to drop the pan and replace the O-ring and trans pan gasket. If that doesn't stop the hemorrhage (I can deal with a little spotting here and there), then I'll yank it and put a 700R4 in it.
I walked in the local chain parts store for ATF. Felt like a total idiot. In my professional life, we didn’t go by type. I repaired foreign cars. We ordered OE for each application. We we sponsored by the dealer and we’re expected to use OE fluids only. We went by part numbers I haven’t owned many autos for myself. Mostly old beaters with manual trans. When I needed fluid a few months ago for my th400, there was these shelves full of everything but what I remember using in the past. Old Fords got type F, GMs got Dex. Had to get my phone out and google which fluid for the th400.
I have a case of A I’ll probably never use…it will go to a swap meet if I ever get to the Long Beach HIPO to sell.
Don't know if it is true but I was told Ford droped type F because of the loss of the uses of Asbestos in clutches.
Walmart is a good source. They actually have a fairly robust supply of Type F, Mercon/Dexron, AFT+4, etc, and keep it stocked. People will shit on the SuperTech brand because it comes from Walmart and is synonymous with cheap Chinese-made garbage, but I've watched plenty of tests on YouTube where the SuperTech, as well as the Amazon Essentials brands, perform as good or better than name brand products.
WHAT IS DEXTRON? Dextron is used to treat hypovolemia (decreased volume of circulating blood plasma), that can result from surgery, trauma or injury, severe burns, or other causes of bleeding. More: https://www.ndrugs.com/?s=dextron
When I got my degree in Automotive Maintenance Technology, we were told Ford started using Type F because it allowed them to use one less clutch plate in each pack. Type F has a higher coefficient of friction than than Dexron, so they say. When I was bracket racing, I used THM 350 and 400, I used Type F because the word on the street was that this is what B&M Trickshift fluid was. F didn’t cost any more than Dexron, and I never had trouble with the racing transmissions. I would still use F if I had an automatic in a hot Rod.
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